>> reporter: is it profitable? >> they can make as much as 50,000 or $60,000 a day just by hitting a couple keys. >> reporter: often the ransom note looks like an official notice from the fbi, accusing you of a crime. >> you have inappropriate content you have stolen content, you have child porn on your machine, that scares people, even if they've never done it. still that the fbi has said we found child porn, that scares people to their very core. >> that's why they pay up? >> yes. >> you should never pay a ransom, even if you do regain access to your computer, the hackers have probably dropped other viruss on to your system. rans ransomware has grown so quickly, the fbi just posted a warning on its internet crimes website. >> it's getting very tedious, and you estimate you've lost business as a result? >> yes, i've been up late just trying to solve the problem. >> with more than 4,000 products in his store.